Circuit breaker with blast valve actuated by a pair of fluid motors



1957 J. w. TIMMERMAN 2,815,419

CIRCUIT BREAKER WITH BLAST VALVE ACTUATED BY A PAIR OF FLUID MOTORS Filed Sept. 15, 1955 2 Sheets-Sheet 1 x Wm m EMMA 1% Dec. 3, 1957 J. w. TIMMERMAN 2,315,419

CIRCUIT BREAKER WITH BLAST VALVE ACTUATED BY A PAIR OF FLUID MOTORS Filed Sept. 13, 1955 2 Sheets-Sheet 2 Patented Dec. 3, 1957 ice CIRCUIT BREAKER WITH BLAST VALVE ACTU- ATED BY A PAIR OF FLUID MQJTORS Julius W. Timruerman, North Weymouth, Ma

to Allis-Chalmers Manufacturing Con: kee, Wis.

This invention relates to circuit interrupting devices and more particularly to blast valve operating mechanism for electric circuit breakers of the fluid operated type.

In a fluid operated electric circuit breaker a source of fluid under pressure is usually connected to a fluid motor for actuating the arcing contacts to open circuit position and to open a blast valve to provide a blast of fluid under pressure adjacent the arcing contacts to extinguish the arc. Heretofore, it has been the practice to provide a contact actuating shaft, driven by the fluid motor, arranged to either provide the full force necessary to crack open the blast valve or to first actuate other valve means to build up a counteracting fluid pressure on the blast valve and then provide the force differential necessary to crack the blast valve open. In either case, however, when it becomes necessary or desirable to accelerate the initial opening movement of the circuit breaker, the adjustments required to maintain the proper sequence of arcing contact separation to blast valve opening tend to become critical and unstable, thereby jeopardizing the interrupting ability of the circuit breaker.

In order to assure the interrupting ability of the circuit breaker, a new and improved operating mechanism is provided which utilizes a fluid motor for providing a force of about eighty percent of the force necessary to crack the blast valve and another fluid operated motor and shaft assembly for separating the arcing contacts and for providing the additional force at the desired time in the contact opening cycle to crack open the blast valve.

It is, therefore, one object of the present invention to provide a new and improved operating mechanism in which one device provides substantially all of the force necessary to actuate an element and another device provides the triggering force necessary to initiate its movement.

Another object of the present invention is to provide a new and improved operating system for a fluid blast type of circuit breaker in which the contact actuating shaft controls the blast valve cracking operation.

A further object of the present invention is to provide a new circuit breaker operating system in which a first pneumatic device applies substantially all of the force needed to crack a blast valve open and a second pneumatic device triggers the blast valve cracking operation and sequentially separates the arcing contacts.

A still further object of the present invention is to provide a new and improved streamlined circuit breaker structure which is compact, eflicient and reliable.

Objects and advantages other than those set forth will be apparent from the following description when read in connection with the accompanying drawings, in which:

Fig. 1 is a diagrammatic view partly in elevation of a circuit interrupting system embodying the present invention;

Fig. 2 is an enlarged detailed view of the blast valve assembly illustrated in Fig. 1;

Fig. 3 is a view in elevation taken along the lines III-III of Fig. 2; and

Fig. 4 is a sectional view taken along the lines IV-1V of Fig. 2.

Referring more particularly to the drawings by characters of reference, Fig. 1 illustrates a circuit breaker including as a constructive element thereof a reservoir 6 constituting a source of supply of fluid under pressure, which will be assumed herein to be compressed air supplied from a suitable compressor (not shown). Although in general, circuit breakers of the type herein considered are provided with a plurality of similar pole structures, one for each phase of a polyphase electric circuit, only one such pole structure or pole unit is shown in the figure and the circuit breaker will be described in detail as if it were of the single pole unit type.

The circuit breaker comprises a fixed arcing contact 7 and a cooperating movable arcing contact 8 connected in an electric circuit through terminal studs 9 and 10. The arcing contacts are mounted to engage within an arcing chamber 11 which is aligned with an arc chute 12. The arcing chamber 11 is axially aligned with a hollow insulator 13 which provides a connection between reservoir 6 and arcing chamber 11 through a suitable blast valve 14 for directing a blast of arc extinguishing fluid under pressure between the arcing contacts and through the arcing chamber 11.

The blast valve 14 requiring a relatively high force to effect initial movement thereof is initially actuated by the combined effort of a high power, short stroke fluid motor 15 and a fluid contact actuating motor 16. Blast valve 14 controls a blast inlet port 18. Motor 15 coaxially arranged with blast valve 14 comprises a cylinder 19, a piston 2d, a piston rod or valve stem 21, a spring 22, and an inlet port 24. Piston 20 is slidably mounted on piston rod 21 but engages a shoulder provided on the piston rod after a predetermined movement thereof in blast valve opening direction.

A solenoid operated valve 25 opens automatically if a fault current occurs on the power circuit controlled. Valve 25 controls the flow of fluid under pressure from reservoir 6 through a pipeline 27, valve 25, pipeline 28 of a control valve 29 and inlet port 24 of cylinder 19 to act on the piston 20 of motor 15.

Valve 29 comprising a valve body 3%), inlet port 31, outlet port 32, valve element 33, valve stem 34 and valve biasing spring 35 is connected by a collapsible linkage 36 to a lever 37 by a pin 38. Lever 37 is pivotally connected at pin 38 to a pair of rocker arms 39 (only one of which is shown in Figs. 1 and 2) loosely mounted on a rocking shaft 40. A linkage 43 connects rocking shaft 40 with the movable sickle shaped arcing contact 8. If arcing contact 8 is in the closed position thereof, valve 29 is in the valve closed position wherein valve element 33 blocks the outlet port 32.

When control valve 29 is actuated to valve open position by fluid under pressure in pipeline 28, the valve element 33 moves against the bias of spring 35 to provide a passage for fluid under pressure to pass from pipeline 28 through inlet port 31, control valve 29, outlet port 32, pipeline 4% to fluid motor 16. When solenoid operated valve 25 recloses it dumps the fluid under pressure in pipeline 23 to atmosphere, thereby permitting spring 35 to reclose valve 29 and cause linkage 36 to collapse.

Fluid motor 16 comprising a cylinder 47 and a piston 48 having a piston rod 49 movable therewith is connected through a connecting rod 50 and a crank 51 to shaft 40. Motor 16 is provided with a dumping valve 52 which releases pressure above piston 48 at or near the end of its upward stroke. Dumping valve 52 is provided with 3 ports 55 which are controlled by a plate 56 biased in port opening direction by a spring 57.

Shaft 40 is provided with a cam 69 which upon rotation of shaft 40 in contact opening direction engages a roller 61 mounted on one end of lever 37, if lever 37 is positioned in the path of movement of cam 60 by control valve 29. Motor 16 which actuates shaft 40 and cam 60 serves as the second motor for providing the additional force needed to crack the blast valve open.

As noted from Figs. 1 and 2 of the drawings, stem 34 of valve element 33 of control valve is connected to the toggle 36 through a clevis 41. In the uppermost position of valve element 33, the toggle 36 is in the overcenter position. The depending rocker arms 39 which are free to rotate about shaft 4t) provide the bearings for pin 38 which in turn provides the bearing for the blast valve actuating lever 37. The blast valve actuating cam 60, which is in fixed relationship to the main shaft til, is shown in Fig. l in the breaker closed position immediately above the cam roll 61 of lever 37. in Fig. 2 the cam 64) is shown in the breaker open position.

Valve actuating lever 37 is free to rotate about pin 38 but is biased by its own gravity component into engagement with an extension of the blast valve stem or piston rod 21.

Initial movement of piston 48 of motor 116 in breaker opening direction initiates clockwise rotation of the main shaft and its valve actuating cam 66. At this time valve stem 34 of control valve 29 has moved toggle 36 to its overcenter position so that cam roll 61 of lever 37 is Within the path of movement of cam 6d. The rotational force of shaft 40 during initial circuit breaker opening movement is transmitted through cam on, cam roll 61 to lever 37 to initiate the opening movement of the blast valve 14 substantially simultaneously with the initial opening movement of the breaker contacts.

When cam 60 communicates through lever 37 to the valve stem 21 a force slightly in excess of the differential between the valve opening force of piston and the force required to cause initial opening movement of the blast valve is imparted to the blast valve 14. Continuation of the rotational movement of cam 60 imparts to lever 37 the clockwise rotational movement required to fully open blast valve 14. Compressed air released from tank 6 by the opening of blast valve 1 into housing 62 is communicated through a passage 63 in the housing wall immediately above the valve stem 21 to cylinder 19 on the side of piston 20 opposite to port 24. The force of an under pressure from passage 63 rapidly neutralizes the pressure on piston Zti from inlet port 2 Hence, when the cam 60 in its continued clockwise rotation disengages the cam roll 61 of lever 37 the last component of opening blas upon the blast valve 14 is removed and the blast valve, under the effect of the air tank pressure, immediately recloses. Spring 22 does not impose significant closing bias upon valve assembly Its primary purpose is to positively seat valve 14 and thereby prevent leakage which would retard initial filling of the air tank 6.

Cam 60 dominates both the blast valve opening and blast valve closing movements of valve stem 21 and the configuration of the cam face can be made to determine precisely the time of opening and closing and the interval of time during which the blast valve remains open.

When the breaker reaches a predetermined position in its opening stroke, port 59 in cylinder 47 of motor 16 is uncovered by piston and air under pressure flows through port 59, pipe 64 to the breaker opening solenoid valve 25 to close the pilot valve thereof shown in Fig. 2. Closing of this pilot valve 34 causes a main valve 83 of solenoid valve 25 to reclose and to open simultaneously an exhaust port 67 to atmosphere on its downstream side. Thus, the supply of compressed air to the blast valve manifold or passage 2% is cut off and the residue therein permitted to escape to atmosphere.

Simultaneously with the collapse of pressure in the manifold or passage 28, which immediately follows the reclosing of the control valve 25, valve element 33 biased downwardly by spring 35 returns to its initial position, thereby causing toggle members 36 to collapse and to rotate rocker member 39 counterclockwise about the main shaft. The consequent displacement of bearing pin 38 causes lever 37 to rotate clockwise about its point of engagement with the valve stem 21, as an instantaneous center of rotation, thereby displacing its cam roll 61 from the path of the valve actuating cam 66. This displaced position of cam roll 61 is its normal position throughout a breaker closing operation. Hence the blast valve actuating cam 60 is effective only during a breaker opening operation.

In practice it is possible for a circuit breaker to be closed against a system fault under such conditions of protective relay time setting that a tripping impulse will be imposed upon the breaker before it has reached its fully closed position.

The effect of such an event upon the operation of the blast valve would be, initially, to retard the closing movement of the valve actuating cam 60, possibly to such a degree that breaker opening motion would be initiated while the cam was still a substantial distance from its normal breaker closed position.

In the event of this possibility, closing movement of the breaker would cease, cam roll 61 would engage the cam 60 before toggle members 36 were in their overcenter position and, when breaker opening movement began, the normal valve opening force of the cam would not be communicated through lever 37 to the stem 21 of valve assembly 14, a consequence of which could be a blast of compressed air, at the time of breaker contact separation, insuflicient to interrupt the fault.

To prevent such malfunction of the blast valve, the valve element 33 is designed to exert a force sutficient to close toggle members 36 irrespective of any obstructing effect that premature engagement of lever 37 with the valve actuating cam 60 may impose. In the event of such premature engagement, the valve element 33, acting through the toggle members 36, causes lever 37 to rotate about the point of engagement of its cam roll 61 with the cam 60, as an instantaneous center of rotation, to crack and drive the valve assembly 14 to its fully open position. Because valve element 33 controls the flow of compressed air to the breaker opening cylinder, as previously described, the proper sequence of breaker contact separation to blast valve opening is maintained.

Closing of the arcing contacts is initiated by energizing a solenoid operated valve 69 which is substantially identical to valve 25. Valve 69 connects reservoir 6 to one end of a fluid motor '70.

Fluid motor 7ft, through the intermediary of a connecting rod and linkage 71, causes counterclockwise rotation of shaft 40 to close the contacts 7, 8. Motor 70 comprises a cylinder 72, a piston 73 and a dump valve 74. Valve 74 is provided with ports '76 which are controlled by a plate 77 biased in port opening direction by a spring 78. The other end of closing motor 70 is connected through an outlet port 79 to solenoid valve 69 through a pipe 75. In the closed position of the breaker, the piston 73 of fluid motor 70 is in its lower position.

The solenoid operated valves 25 and 69 are substantially identical and are of the type shown and claimed in Julius W. Timmerinans U. S. Patent 2,778,379 granted January 22, 1957.

Valve 25 comprises a casting forming a cylinder 80 provided with a fluid admission opening or port 81 and with an exhaust opening or port 82. Port 81 is connected to pipeline 27 and port 82 is connected to pipeline 28. Cylinder 80 is provided with a differential piston or main valve member 33 which is so arranged in cylinder 80 to provide a passage of predetermined cross section between the lower side of main valve member 83 and the upper side of member 83. Cylinder 80 is provided with a pilot valve 84 the opening of which initiates operation of the main valve member 83. Pilot valve 84 is arranged within a casting 85 which is inserted in cylinder 80. A spring 86 biases valve 84 to valve closed position. Valve 84 is provided with a throttling tip 87 which provides a definite piston area. A small amount of air through the pilot valve 84 lifts the pilot disk or tip 87 high enough against the action of spring 86 to make the overall diameter of piston 88 effective in lift against spring 86. Piston 88 is fitted into casting 85 so as to provide a passage of predetermined cross section for the flow of air from the lower to the upper side of the piston. Piston 88 has the upper side thereof vented to atmosphere through a plurality of vents 89. A resilient sealing material 90 is arranged within piston 88 to form a tight seal when the pilot valve 84 is closed. When the main valve member 83 is moved away from annular valve seat 120 so as to provide a direct passageway between ports 81 and 82 a valve member 121 connected to piston operated valve member 83 by a stem 122 closes opening 67 to prevent the escape of air to atmosphere through opening 67.

The pilot valve 84 is locked closed by a spring biased lever arm 91 which abuts against a push rod 92.. Push rod 92 abuts against the pilot valve stem. Lever arm 91 is pivotally mounted at 93 and is arranged to be secured at 94 to an armature 95 of a solenoid 96. Solenoid 96 further comprises a coil 97 and a core or casting 98 of paramagnetic material.

Spring 101 biasing lever arm 91 in valve closing direction is strong enough to hold the pilot valve closed once it is closed but is not strong enough to close the pilot valve once it is sealed open.

Casting 98 provides at the lower end thereof a cylinder 102 of nonmagnetic material which is fitted with a piston 103 of paramagnetic material. Piston 103 forming a part of a magnetic pole member 105 is biased to its lower position by spring 104 but when actuated upward moves magnetic pole member 105. Pole member 105 actuates armature 95 upward and rotates counterclockwise lever arm 91. Lever arm 91 then locks pilot valve 84 in closed position.

Casting 98 as shown more clearly in U. S. Patent 2,778,379 heretofore referred to includes two members arranged one at each end of cylinder 102 providing pole surfaces for magnetically locking the piston 103 in one of two positions.

Piston 103 of valve mechanism may be actuated by the fluid under pressure in cylinder 47 of fluid motor 16 through a port 59 and a pipeline 64. Piston 103 of valve 28 may be actuated by fluid under pressure from cylinder 72 of fluid motor 70 through pipeline 75 or from fluid under pressure in pipeline 28 through a pipeline 100.

A manual emergency pilot valve tripping mechanism may be provided for opening the main valve member 83, if so desired.

Upon the occurrence of a fault condition on the power circuit, solenoid coil 97 of the valve 25 is energized. Armature 95 is actuated to rotate lever arm 91 clockwise about its pivot point 93 to unlock the pilot valve 84. If the fluid pressure in reservoir 6 is below a predetermined value the leakage of air past main valve member 83, pilot valve 84 and piston 88, will not be enough to lift the pilot valve 84 appreciably from its valve seat. At a predetermined reservoir pressure the leakage of air past main valve member 83 creates a pressure between main valve member 83 and pilot valve 84 great enough to lift the tip 87 of pilot valve 84 to a point where the rate of flow around tip 87 is great enough to build up pressure under piston 88 to raise and snap the pilot valve 84 to its open position and to hold it open. The pressure between main valve member 83 and piston 88 will be reduced to a predetermined low value, thus causing the pressure on the upstream side or" main valve member 83 to actuate member 83 to Valve open position and to hold it open. The leakage of air past member 83 When in its open position is still great enough to hold open the pilot valve 84. Spring 86 has enough force to hold the pilot valve closed, but not enough force to close it once the pilot valve is sealed open.

Compressed air is admitted by solenoid valve 25 to the pipeline 28 and transmitted therein upwardly and rearwardly to exert pressure on piston 20 and thereby upon the stem of valve assembly 14 in a valve opening directicn. The effective area of piston 20 is so chosen that it exerts upon the stem of the blast valve 14 a force in the order of eighty percent of that required to crack the valve open.

Simultaneously with the application of compressed air to motor 15, compressed air from pipeline 28 is trans mitted directly upward through inlet port 31 to exert pressure upon the valve element 33 which in its upward movement uncovers outlet port 32 in the wall of valve body 30. Air under pressure from pipeline 28 then flows through outlet port 32, pipeline 44 to cylinder 47 to fluid motor 16. Thus, valve 29 controls the time of actuation of the circuit breaker opening motor 16 and provides a passage when in valve open position for fluid under pressure to flow to motor 16. The fluid supply means through pipe 28 applies a predetermined opening pressure to the blast valve 14 and the control valve 29 and sequentially applies fluid under pressure to motor 16 to open the arcing contacts. The upward movement of valve element 33 is tranmitted through clevis 41 to the toggle linkage 36. Linkage 36 is moved to its predetermined overcenter position by valve element 33 when it reaches its uppermost or valve open position. The upward movement of valve element 33 and the consequent movement of linkage 36 to its overcenter position causes cam roll 61 of lever 37 to be moved within the path of movement of cam 68 on shaft 40. Initial movement of piston 48 of motor 16 in breaker opening direction causes clockwise rotation of shaft 40 and cam 60. The rotational force of cam 68 is immediately applied to lever 37 through cam roll 61 to initiate or trigger the opening movement of blast valve 14 substantially simultaneously with the initial opening movement of the circuit breaker contacts. Cam tit furnishes the additional force needed to crack the blast valve open. Continuation of the rotational movement of the cam imparts to lever 37 the clockwise rotational movement required to fully open blast valve 14.

Compressed air released from tank 6 by blast valve 14 flows through the passage 63 into the chamber of cylinder 19 on the driven side of piston 20 and builds up a neutralizing pressure on piston 20 which upon the release of cam roll 61 by cam 68 permits the compressed air in tank 6 to bias the blast valve 14 to valve closed position.

When the movable arcing contact 8 reaches a predetermined position in its opening movement piston 48 of motor 16 has just passed port 59 and air under pressure passes through port 59, pipeline 64 to the under side of piston 103 arranged in cylinder 182.

Piston 103 and member 185 are actuated upward and push armature upward to rotate lever arm 91 counterclockwise. Push rod 92 is slidably mounted in a cap 119 and is actuated by lever arm 91 to force pilot valve closed, thereby allowing pressure to build up behind main valve member 83 to close it. Once the pilot valve 84 has been closed by an external force, springs 86 and 113 1 are strong enough to hold it closed.

When coil 97 is energized, piston 103 of pole member is magnetically locked or sealed in one of two possible positions. If the pressure in pipeline 64 is below a predetermined value piston 183 is in its lower position. The magnetic flux passing through casting 98 passes through the lower pole surfaces and piston 103 to magnetically lock the piston 103 in its lower position. The magnetic flux in casting 98 attracts armature 95 and draws it down to pole member 105, causing lever arm 91 to rotate clockwise and spring 101 to be compressed. Clockwise rotation of lever arm 91 removes the external force from the stem of the pilot valve 84. In the event that coil 97 remains energized after the contacts 7, 8 have separated a predetermined distance, air from pipelines 28 and 44 passes through fluid motor 16, port 59 in cylinder 47 into pipeline 64. Fluid under pressure in pipeline 64 forces piston 103 and magnetic pole member 105 up and away from the lower pole surface. As the piston 103 reaches the upper limit of its travel the piston 103 is snapped into engagement and is magnetically sealed and locked in the upper position against the upper pole surface. The piston 103 remains in its upper position against the upper pole surface as long as coil 97 remains energized with a predetermined current.

The upward travel of the pole member 105 pushes armature 95 upward and by virtue of the counterclockwise rotation of lever arm 91 forces the pilot valve 84 closed. As the pilot tip 87 begins to throttle, spring 101 forces closed the pilot valve 84 and holds it closed. Continued energization of the coil 97 holds piston 103 against the upper pole surfaces and lever arm 91 holds the pilot valve 84 closed even though the pneumatic pressure in line 64 is greatly reduced.

In the event of a flick operation of a control button which would energize coil 97 only long enough to allow the pilot valve 84 to lift and seal open, the pilot valve 84 would remain open until the valve mechanism 25 has gone through a complete operation. After the pilot valve has opened, spring 101 is not strong enough to close the valve and compressed air flowing through motor 16 and pipe 64 must raise piston 103 and pole piece 105 to rotate counterclockwise lever arm 91 to move the pilot valve 84 in valve closing direction to the point where the spring 101 takes over and completely closes the pilot valve 84 and the main valve member 83.

The circuit breaker arcing contacts are closed by energizing the coil 97 of solenoid valve 69. This valve operates in the same manner as valve 25 to allow fluid under pressure from reservoir 6 through the main valve member 83 to the fluid motor 70. The actuation of fluid motor 70 closes the arcing contacts 7, 8.

Pipelines 75 and 100 are connected to the upper side of casting 98 and actuate piston 103 of valve 69 downward to the lock pilot valve closed position during a circuit breaker opening operation. Thus, if an opening operation is initiated while the breaker is in the act of closing, the opening valve will take preference.

Although but one embodiment of the present invention has been illustrated and described, it will be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the spirit of the invention or from the scope of the appended claims.

It is claimed and desired to secure by Letters Patent:

1. In a fluid blast circuit interrupter, the combination comprising a source of fluid under pressure, separable arcing contacts for establishing an arc, a blast valve for controlling a fluid blast from said source for extinguishing the are drawn upon separation of said contacts, a first motor for exerting an opening force on said blast valve, a second motor for separating said arcing contacts, means for simultaneously actuating said firs-t motor to apply a predetermined opening pressure to said blast valve and said second motor to separate said contacts, and means operable by said second motor upon movement of said contacts in opening direction for exerting the additional force needed on said blast valve to crack said blast valve open, said first motor and said second motor acting substantially simultaneously on said blast valve to crack said blast valve open.

2. In a fluid blast circuit interrupter, the combination comprising a source of fluid under pressure, separable arcing contacts for establishing an arc, a blast valve for controlling a fluid blast from said source for extinguishing the are drawn upon separation of said contacts, a first motor for exerting an opening force on said blast valve, a second motor for separating said arcing contacts, means for controlling the time of actuation of said second motor, means for simultaneously actuating said first motor to apply a predetermined opening pressure to said blast valve and to said control means to actuate said second motor to separate said contacts, and means operable by said second motor upon movement of said contacts in opening direction for cracking said blast valve, said first motor and said second motor acting substantially simultaneously on said blast valve to crack said blast valve open.

3. In a fluid blast circuit interrupter, the combination comprising a source of fluid under pressure, separable arcing contacts for establishing an are, a blast valve for controlling a fluid blast from said source for extinguishing the arc drawn upon separation of said contacts, a first fluid operated motor comprising a cylinder and a piston for exerting an opening force on said blast valve, a second fluid operated motor comprising a cylinder and a piston for separating said contacts, valve means for controlling the time at which fluid under pressure is supplied to said second motor, means for simultaneously supplying fluid under pressure to said first motor to apply a predetermined opening pressure to said blast valve and to said valve means to actuate said valve means to valve open position, said valve means upon actuation to valve open position providing a passage for fluid under pressure to flow to said second motor to open said contacts, and means operable by said second motor upon movement of at least one of said contacts in opening direction for acting on said blast valve simultaneously with said first motor for cracking said blast valve.

4. In a fluid blast circuit interrupter, the combination comprising a source of fluid under pressure, separable arcing contacts for establishing an are, a blast valve for controlling a fluid blast from said source for extinguishing the are drawn upon separation of said contacts, a first motor for exerting a first opening force on said blast valve, a second motor for separating said contacts and for exerting a second opening force on said blast valve, pivotally mounted lever means actuable by said second motor during a contact opening operation for exerting said second opening force on said blast valve when said lever means is in a predetermined position, said first motor and said second motor operating simultaneously to crack said blast valve open, valve means for positioning said lever means in said predetermined position, and means for simultaneously actuating said first motor to apply a predetermined opening pressure to said blast valve and said valve means to valve open position to position said lever means in said predetermined position, said valve means upon actuation to valve open position actuating said second motor to open said contacts.

5. In a fluid blast circuit interrupter, the combination comprising a source of fluid under pressure, separable arcing contacts for establishing an arc, a blast valve for controlling a fluid blast from said source for extinguishing the are drawn upon separation of said contacts, a first fluid operated motor comprising a cylinder and a piston for exerting a first opening force on said blast valve, a second fluid operated motor comprising a cylin der and a piston for separating said contacts, pivotally mounted lever means actuable by said second motor for exerting a second opening force on said blast valve when said lever means is in a predetermined position, said first motor and said second motor operating simultaneously to crack said blast valve open, valve means for controlling the time at which fluid under pressure is supplied to said second motor and for positioning said lever means in said predetermined position, and means for simultaneously supplying fluid under pressure to said first motor to apply a predetermined opening pressure to said blast valve and to said valve means to actuate said valve means to valve open position to position said lever means in said predetermined position, said valve means upon actuation to valve open position providing a passage for fluid under pressure to flow to said second motor to open said contacts.

6. In a fluid blast circuit interrupter, the combination comprising a source of fluid under pressure, separable arcing contacts for establishing an arc, a blast valve for controlling a fluid blast from said source for extinguishing the arc drawn upon separation of said contacts, a first fluid operated motor comprising a cylinder and a piston for exerting a first opening force on said blast valve, a second fluid operated motor comprising a cylinder and a piston for separating said contacts, a collapsible linkage means for operatively connecting said second motor to said blast valve during a contact opening operation for exerting said second opening force on said blast valve when said linkage means is in an overcenter position, said first motor and said second motor operating simultaneously to crack said blast valve open, valve means for controlling the time at which fluid under pressure is supplied to said second motor and for positioning said linkage means in said overcenter position during a valve opening operation, and means for simultaneously supplying fluid under pressure to said first motor to apply a predetermined opening pressure to said blast valve and to said valve means to actuate said valve means to valve open position, said valve means upon actuation to valve open position providing a passage for fluid under pressure to flow to said second motor to open said contacts.

7. In a fluid blast circuit interrupter, the combination comprising a source of fluid under pressure, separable arcing contacts for establishing an are, a blast valve for controlling a fluid blast from said source for extinguishing the are drawn upon separation of said contacts, a first fluid operated motor comprising a cylinder and a piston for exerting a first opening force on said blast valve, a second fluid operated motor comprising a cylinder and a piston for separating said contacts, means comprising a pivotally mounted lever actuable by said second motor for exerting a second opening force on said blast valve and a collapsible linkage for operatively connecting said second motor to said lever when in an overcenter posi tion, said first motor and said second motor operating simultaneously to crack said blast valve open, valve means for controlling the time at which fluid under pressure is supplied to said second motor and for positioning said linkage in said overcenter position When moved to valve open position, and means for supplying fluid under pressure to said first motor and to said valve means to actuate said valve means to valve open position, said fluid supply means applying a predetermined opening pressure to said blast valve and said valve means and sequentially applying fluid under pressure to said second motor to open said contacts.

8. In a fluid blast circuit interrupter, the combination comprising a source of fluid under pressure, separable arcing contacts for establishing an are, a blast valve for controlling a fluid blast from said source for extinguishing the are drawn upon separation of said contacts, a first fluid operated motor comprising a cylinder and a piston for exerting a first opening force on said blast valve, a second fluid operated motor comprising a cylinder and a piston for separating said contacts, means comprising a pivotally mounted lever actuable by said second motor for exerting a second opening force on said blast valve and a collapsible linkage for operatively connecting said second motor to said lever When in an overcenter position, said first motor and said second motor cracking said blast valve open, valve means comprising a valve element and valve stem for controlling the time at which fluid under pressure is supplied to said second motor, said valve stem being connected to said linkage for positioning said linkage in said overcenter position during a valve opening operation, means for simultaneously supplying fluid under pressure to said first motor to apply a predetermined opening pressure to said blast valve and to said valve means to actuate said valve means to valve open position, said valve means upon actuation to valve open position providing a passage for fluid under pressure to flow to said second motor to open said contacts, and spring biasing means connected to said valve stem for causing collapse of said linkage during a valve closing operation.

9. In a fluid blast circuit interrupter, the combination comprising a source of fluid under pressure, separable arcing contacts for establishing an are, a blast valve for controlling a fluid blast from said source for extinguishing the arc drawn upon separation of said arcing contacts, a first fluid operated motor comprising a cylinder and a piston for exerting an opening force on said blast valve, a second fluid operated motor comprising a cylinder and a piston arranged to operate in sequence with said blast valve for separating said arcing contacts, a shaft mounted for rotation upon movement of said second motor, a cam secured to said shaft, pivotally mounted lever means actuable by said cam for exerting an opening force on said blast valve, valve means for controlling the time at which fluid under pressure is supplied to said second motor during a valve opening operation, and means for simultaneously supplying fluid under pressure to said first motor to apply a predetermined opening pressure to said blast valve and to actuate said valve means to valve open position, said valve means upon actuation to valve open position providing a passage for fluid under pressure to flow to said second motor to open said arcing contacts, said lever means operable by said second motor upon movement of said arcing contacts in opening direction for exerting the additional force needed on said blast valve to crack said blast valve open.

It). in a fluid blast circuit interrupter, the combination comprising a source of fluid under pressure, separable arcing contacts for establishing an arc, a blast valve for controlling a fluid blast from said source for extinguishing the are drawn upon separation of said contacts, a first fluid operated motor comprising a cylinder and a piston for exerting a first opening force on said blast valve, a second fluid operated motor comprising a cylinder and a piston for separating said contacts, a shaft mounted for rotation upon movement of said second motor, a cam secured to said shaft, means comprising a pivotally mounted lever actuable by said cam for exerting a second opening force on said blast valve and a collapsible linkage for operatively connecting said cam to said lever when in an overcenter position, said first motor and second motor cracking said blast valve open, valve means comprising a valve element and a valve stem for controlling the time at Which fluid under pressure is supplied to said second motor during a contact opening operation, said valve stem being connected to said linkage for positioning said linkage in said overcenter position during a valve opening operation, and means for simultaneously supplying fluid under pressure to said first motor to apply a predetermined opening pressure to said blast valve and to said valve means to actuate said valve means to valve open position.

11. In a fluid blast circuit interrupter, the combination comprising a source of fluid under pressure, separable arcing contacts for establishing an arc, a blast valve for controlling a fluid blast from said source for extinguishing the are drawn upon separation of said arcing contacts, a first motor for exerting an opening force on said blast valve, a second motor for separating said arcing contacts, a shaft mounted for rotation upon movement of said second motor, a cam secured to said shaft, pivotally mounted lever means actuable by said cam for exerting an opening force on said blast valve, and means for energizing said first motor to apply a predetermined opening pressure to said blast valve and said second motor to actuate said shaft and said cam to open said arcing contacts, said lever means engaging said cam upon rotation of said shaft in contact opening direction and rotating about said cam as an instantaneous center of rotation for exerting the additional force needed on said blast valve to crack said blast valve open.

12. In a fluid blast circuit interrupter, the combination comprising a source of fluid under pressure, separable arcing contacts for establishing an are, a blast valve for controlling a fluid blast from said source for extinguishing the are drawn upon separation of said arcing contacts, a first fluid operated motor comprising a cylinder and a piston for exerting an opening force on said blast valve, a second fluid operated motor comprising a cylinder and a piston for separating said arcing contacts, a shaft mounted for rotation upon movement of said second motor, a cam secured to said shaft, pivotally mounted lever means actuable by said cam for exerting an opening force on said blast valve, and means for supplying fluid under pressure to said first motor to apply a predetermined opening pressure to said blast valve and to said second motor to actuate said shaft and said cam to open said arcing contacts, said lever means engaging said cam upon rotation of said shaft in contact opening direction and rotating about said cam as an instantaneous center of rotation for exerting the additional force needed on said blast valve to crack said blast valve open.

13. In a fluid blast circuit interrupter, the combination comprising a source of fluid under pressure, separable arcing contacts for establishing an arc, a blast valve for controlling a fluid blast from said source for extinguishing the are drawn upon separation of said arcing contacts, a first fluid operated motor comprising a cylinder and a piston for exerting an opening force on said blast valve, a second fluid operated motor comprising a cylinder and a piston for separating said arcing contacts, a shaft mounted for rotation upon movement of said second motor, a cam secured to said shaft, pivotally mounted lever means actuable by said cam for exerting an opening force on said blast valve, valve means for controlling the time at which fluid under pressure is supplied to said second motor during a valve opening operation, and means for supplying fluid under pressure to said first motor to apply a predetermined opening pressure to said blast valve and to actuate said valve means to valve open position, said valve means upon actuation to valve open position providing a passage for fluid under pressure to flow to said second motor to open said arcing contacts, said lever means engaging said cam upon rotation of said shaft in contact opening direction and rotating about said cam as an instantaneous center of rotation for exerting the additional force needed on said blast valve to crack said blast valve open.

14. In a fluid blast circuit interrupter, the combination comprising a source of fluid under pressure, separable arcing contacts for establishing an arc, a blast valve for controlling a fluid blast from said source for extinguishing the are drawn upon separation of said contacts, a fluid operated motor comprising a cylinder and a piston for exerting an opening force on said blast valve, a second fluid operated motor comprising a cylinder and a piston for separating said arcing contacts, means for simultaneously actuating said piston of said first motor in one direction to apply a predetermined opening pressure to said blast valve and said second motor to separate said contacts, means operable by said second motor upon movement of said contacts in opening direction for exerting the additional force needed on said blast valve to crack said blast valve open, and means operable by the fluid blast from said blast valve for actuating said piston of said first motor in a second direction to close said blast valve.

15. In a fluid blast circuit interrupter, the combination comprising a source of fluid under pressure, separable arcing contacts for establishing an arc, a blast valve for controlling a fluid blast from said source for extinguishing the arc drawn upon separation of said arcing contacts, a first fluid operated motor comprising a cylinder and a piston for exerting an opening force on said blast valve, a second fluid operated motor comprising a cylinder and a piston arranged to operate in sequence with said first motor for separating said arcing contacts, a shaft arranged for rotation upon movement of said second motor, a cam secured to said shaft, pivotally mounted lever means actuable by said cam upon engagement therewith for a predetermined time for exerting an opening force on said blast valve, means for simultaneously supplying fluid under pressure to said first motor to apply a predetermined opening pressure to said blast valve and said second motor to actuate said shaft and said cam to open said arcing contacts, said lever means operable by said second motor upon movement of said arcing contacts in opening direction for exerting the additional force needed on said blast valve to crack said blast valve open, and means operable by the fluid blast from said blast valve for actuating said piston of said first motor in a second direction to close said blast valve upon disengagement of said lever means from said earn.

References Cited in the file of this patent UNITED STATES PATENTS 2,292,096 Thumin et al Aug. 4, 1942 2,597,047 Ainsworth May 20, 1952 2,633,512 lansson Mar. 31, 1953 2,681,958 Linde June 22, 1954 

